This invention relates to graft copolymers of xanthomonas hydrophilic colloid and partially N-aminoalkylated acrylamide. The xanthomonas colloid is an anionic heteropolysaccharide containing mannose, glucose, and glucuronic acid groups. The copolymerization of the anionic polymer with acrylamide is known and its method of preparation is described in the U.S. Pat. No. 3,708,446. However, these copolymers are quite stable in aqueous media to changes in pH ranging from 2 to 12 indicating that they are very weak ionic polymers. It is desirable to create an amphoteric polymer which can be used either as a cationic polymer or an anionic polymer.
To create the desired new and easily ionizable copolymers, the amino functions of the acrylamides present in the xanthomonas colloid-acrylamide copolymers are partially converted to aminoalkylamines via Mannich reaction. Although the method has been applied to polyacrylamide, it has not been used in modifying any of the xanthomonas-acrylamide copolymers which incorporate all the xanthomonas heteropolysaccharide functional groups such as hydroxyl, carboxyl, ester and ketal. Surprisingly, these active functional groups have not interfered with the aminoalkylation.
Therefore it is an object of the present invention to generate new amphoteric graft copolymers of xanthomonas hydrophilic colloid and partially N-aminoalkylated acrylamide which retain many of the desirable characteristics of the anionic heteropolysaccharide xanthomonas colloid while at the same time, having the desirable cationic characteristics of the N-aminoalkylated acrylamide.
An additional object of this invention is to provide a suitable aminoalkylation process under well-controlled conditions for the creation of these novel copolymers.